The present invention relates to devices for moving dies in machines for the manufacture of twisted wire articles with alternating direction of twist, such as for making sawing ropes to be used for abrasive sawing of natural stone or for making electric cables.
At present, rotary machines are widely used for making twisted articles with alternating direction of twist. In such machines, a rotor made in the form of a basket or cigar is caused to rotate reversibly to twist an article. Heavy weight and large radius of the rotor do not permit operation at high speed when frequent changing of rotation direction since it results in heavy inertial and dynamic machine loads and requires high power consumption.
Therefore the manufacture of rope-type articles with alternating direction of twist on rotor-type machines is rather ineffective so that rotor-less machines are coming into wider use for the same purpose.
USSR Inventor's Certificate No. 501,127 discloses a device for moving dies in a rotor-less machine for making twisted wire articles with alternating direction of twist. The device is provided with guides fixed on the machine bed along the axis of pulling the article. A slider having a lower block rigidly fixed thereto is mounted in the guides for reciprocations. An upper die cooperates with the lower block by means of a wedge-type clamping mechanism.
However, the wedge-type clamping mechanism cannot ensure complete prevention of the article from rotating thus resulting in lower quality of twisted articles.
An increase in the wedging force to improve the bond between the dies and the article requires the use of a more powerful drive for moving the dies thus making the machine kinematics more sophisticated. Moreover, with an increase in the wedging force, the required unwedging force also increases to the same extent. It should be noted that load bearing capacity of twisted articles with alternating direction of twist under tension is limited due to untwisting of members of the article at the points of changing the direction of twist.
In view of an evergrowing demand for building and decorative materials made of natural stone, the demand for ropes with alternating direction of twisting used for abrasive cutting of stone also grows. However, known machines cannot cope with the growing demand for such articles so that improvement of these machines is now a long felt need.
It should be noted that the provision of rotor-less machines for the manufacture of electric cables would enable simplification of the production process and reduction of cost in making such articles.